1. Field Of The Invention
The field of art to which this invention pertains is that of multiple plate fluid-pressure actuated type of clutches used in power-shift transmissions, and, more particularly, to a tool used for compressing piston return springs so as to permit the ready manual insertion or removal of a snap ring that secures the piston return spring retainer cup.
2. Description Of The Prior Art
Constant-mesh powershift transmissions of the type shown, for example, in prior U.S. Pat. No. 3,893,345 generally utilize multiple plate, fluid-actuated clutches. These clutches generally include an internally splined drum affixed to a first rotatable transmission member, an externally splined hub affixed to a second rotatable transmission member and a plurality of interleaved friction plates splined alternately to the hub and drum. The friction plates are confined between an annular end plate and a fluid pressure actuated piston which serves to press the friction plates together, thereby connecting the hub and drum for conjoint rotation in a manner well known in the art. Generally, the piston is biased in the direction away from the friction plates via a piston return spring confined between the piston and an annular spring retainer cup that is secured against axial movement by a snap ring located in a snap ring groove in the first rotatable transmission member.
The force of the clutch return spring, which is generally from 100 to 150 pounds, must be overcome in order to install the retainer cup snap ring. Prior art assembly or disassembly of this type of fluid actuated type clutch involves removing the entire clutch from the transmission and then, after further removal of the interleaved friction plates, inserting the clutch assembly onto an arbor press and compressing the spring by the use of a cylindrical sleeve which has an opening through which a snap ring removal tool can be manually inserted for removing, or in the case of assembly, inserting the snap ring.
Since it is a common practice to service these transmissions and clutches in the field, arbor presses are not always readily available. In addition, in some instances, it would be possible to service the clutch without removing it from the transmission if it were possible to add or remove the snap ring and clutch piston return spring without the use of an arbor press.